The number of apps available in Microsoft’s Windows Phone Marketplace is dwarfed by the number of apps available on the Apple App Store and Google Play. But soon, those of you who took a risk with a Windows phone won’t have to fret that the world’s favorite photo app isn’t available: Instagram is coming to Windows Phones.

The Verge was initially tipped off about the app’s existence when a reader thought he noticed Instagram featured in the Nokia promo video featuring its PureMotion technology. This wouldn’t be the first time Nokia inadvertently unveiled a big new app in a promo video; Nokia’s promo video demonstrating a Lumia charging on a wireless charging dock “accidentally” unveiled Skype’s Windows Phone app in action.

We re-watched the video and could make out what might be the Instagram app during the PureMotion demo, but we couldn’t be sure. The tile in question is displayed toward the end of the promo clip and displays the words “Walk Up,” and is accompanied by a comment and “Like” button that’s uncanny to the silhouette of the talk balloon and heart button that you would find on Instagram. But a secondary explanation could be that the app is actually Vimeo.

Whatever the case may be, The Verge has confirmed that Instagram will be making its way onto Windows Phones.

ZDNet theorized that Facebook’s purchase of Instagram would result in the app coming to Windows Phones, and it looks like they were right. Facebook has a tight-knit relationship with Microsoft, which purchased a stake in Facebook back in 2007. Further, the Federal Trade Commission finally approved the Instagram and Facebook deal after conducting an investigation due to antitrust concerns. Had the deal been blocked by the FTC, Instagram would have walked away with $200 million from Facebook for its troubles.

A consumer’s decision on purchasing a smartphone these days has a lot to do with what the complimenting app store has to offer. Microsoft’s Marketplace has cracked the 100,000 app mark, while Apple has broken 700,000 apps. The Google Play store is hot on Apple’s tail with more than 500,000 apps. That said, the number of apps isn’t everything; a large number of apps go unused simply by getting lost in the mix. In other words, it’s a matter of quality over quantity — how many of the main app titles an app store can get from existing popular apps like Skype, Instagram, and Angry Birds. Of course getting apps like Skype, Instagram, and even Angry Birds onto the Marketplace came courtesy of existing Microsoft relationships.

Windows Phone users — are you excited for Instagram? Let us know your thoughts in the comments.

[Update: According to VentureBeat, Instagram is not heading to Windows Phone anytime soon. A source says no such application is going to be released, although representatives wouldn’t comment on potential products. And there you have it: Instagram’s Windows Phone fate continues to hang in the balance.]